Annunciator for telephonic circuits



(No Model.)

' T. SPENCER.

ANNUNGIATOR FOR TELEPHONIG CIRCUITS.

I No. 532,605. Patented an. 15, 1895.

lhT emfor.

lllllllllll a "mm! A nnummul IIIII"! THEODORE SPENCER, CF- CAMBRIDGE,ASSIGNOR TO THE AMERICAN BELL PATENT OFFICE,

' TELEPHONE'COMPANY,-OF BOSTON, MASSACHUSETTS.-

ANNUNCIATOR FOR T ELEPHONIC CIRCUITS- SPECIFICATION forming part ofLetters Patent No. 532,605, dated January 15, 1895.

' Application filed September 10, 1894. Serial No. 522,611. (No model.)

To all whofit it may concern:

Beit known that I, THEODORE SPENCER, residlng at Cambridge, in thecounty of Middlesex and State of Massachusetts, have invented certainImprovements in Annunciators for Telephonic Circuits, of which thefollowing is a specification.

This invention relates to'visible signal indicators or annunciators fortelephonic circuits; and more specifically to that class which arearranged to display theindicating device when the circuit is closed, andto withdraw the same, thereby automatically resetting the signal, when.the circuit is reopened. It is evident that the withdrawal equally withthe display of the indicating device has a defi-.

nite signification, and may be readily understood as a signal.

The object of the invention is to provide a self-setting indicator,simple in construction, and trustworthy in operation, adapted to giveone indication under the application of a steady electric current, andto be automatically reset on the withdrawal of such ourrent, whereby isafforded a reliable signal indicating at one point of a circuit anychange in connections made at another point.

The invention consists in a signal device comprising an electromagneticspool; an armature and armature lever therefor being weighted at itsfree end; and a signal shutter normally retracted and held out of sightby the weighted end of the armature lever, which as long as the magnetremains unexcited,

rests upon a projecting heel piece with which it is provided; butadapted when freed from such weight to fall in virtue of its own weight,and display itself at a suitable aperture.

It also consists in combining in a self-setting annunciator the saidshutter or signal plate tending when'untra'mmeled by an opposing forceto fall and display itself in virtue of its own weight, and the weightedarmature lever normally preventing such a display by exercising asuperior counter weight v on a lever extension of the said shutter, withan electromagnet of lowimpedance adapted to be placed in a telephoniccircuit without detriment to the transmission of voice currents.

it further consists in combining in a signal indicating appliance, asignal plate or shutter tending by reason of its own weight to hangvertically, and display the signal; a superior weight normally acting inopposition to the said tendency and thereby holding the said signalplate in a horizontal and invisible position; and an electromagnetcontrolling the said superior weight, and adapted when excited tofree't-he said signal plate therefrom, whereby the signal may beactuated from any point in a circuit containing the said magnet.

In the drawings, Figure 1 is a side view mostly in vertical section,showing an annunciator embodying the invention, and Fig. 2 is a diagramshowing the annunciator in circuit with a spring jack, plug and battery;the said battery or any equivalentgenerator being applied bythe'insertion of the plug.

A represents the annunciator in both fig ures, and referring especiallyto Fig. 1, a is a soft iron core on pole piece secured to a soft ironshell or tube e at its front end a, and to the iron bar t, which ifdesired may be formed to constitute the support of a number ofannunciators when arranged for central office switchboards.

Fig. 3 is a rear view of the annunciator showing the two electricalconnections thereof; and Fig. 4 is a diagram indicating the magnetizingand shunt winding connections thereof.

The rear ends of the core and tube form virtually the two poles of a Umagnet. The helices of the core are wound between the non-conducting endpieces b and 19 It is often desirable that signals or annun ciators ofthis character shall be placed directly in a telephone circuit, toindicate at one station, changes in the electrical connectained byproviding the non-magnetizinghelix with a non-inductive shunt circuit ofsuitable resistance, and for convenience I wind the said shunt round thecore, and inclose it within the iron surrounding tube. A constructionwhich has proved satisfactory, is to arrange the two windings on thespool in parallel with each other; the magnetizing helix 0 consisting ofa single conductor of silk covered No. 28 copper wire wound to aresistance of seventeen ohms; while the shunt winding (1 constituting apath of low impedance for voice currents is made of No. 30 silk coveredGerman silver wire, wound double to prevent self-induction. The two endsof both windings connect with the same terminals w to which in turn areelectrically united with the circuit wires. A magnet so made, is of lowimpedance as respects telephonic or other rapidly changing currents.

The armature f is pivoted at g, and may have a limit screw o. It carriesa lever or arm h which extends forward to the front end of theannunciator, and terminates -in a downwardly projecting end j. A shortdistance behind the projection j the lever has an enlargement i to serveas a weight to depress the end of the arm when the electro magnetic corea is not excited, and its armature'f attracted. A signal plate orshutter which may be made of any suitable material, such as aluminium,is hung in pivots m, and tends in virtue of its own gravity to hangvertically and to display itself as indicated in broken lines at theopening or aperture 0 in the frame plate W. This signal plate has ashort lever or heel 'piece I secured to its top edge and extendingforwardly therefrom, and with this lever the projecting end j of thearmature lever or rod engages normally or when the electromagnet isunexcited. By its weight which is superior to that of the shutter on theother side of the pivots, the said shutter is prevented from yielding toits own tendency to assume a vertical position where it is displayed,and is forced away from the aperture 0, and into a horizontal position,(shown in full lines,) where it is out of sight.

In Fig. 2, the armature is represented as being connected with itsoperating battery in a telephone circuit, and as indicating at a distantstation, the fact that such circuit is engaged.

L is the telephone line extending from a spring jack 8, to one of thesignal terminals w, and thecircuit continues through the windings ofsaid signal, and from their remaining terminal to earth by the wire 1'.Thisline forms the actual conversation circuit, or a part thereof, asindicated by the presence of the telephones t, 25

A plug 10 to which is connected a battery or any suitable generator B,having its other pole connected to the earth or equivalent returnconductor, is shown as inserted in the spring jack, so that the currentof the generator passes to line. If the plug were withdrawn, the springof the jack would rest on its insulated anvilcontact and the line wouldbe grounded direct. Placed, as shown, the

"current from the battery magnetizes the core of the signal indicator bymeans of the exciting helix 0, the armaturefiis attracted thereto, andthe weight at the frontend of the armature lever or rod is lifted fromthe short lever lot the signal shutter. The shutter thus released fromthe influence of its superior counterweight yields to its tendency tofall by reason of its own weight, and appears at the aperture 0. Itsappearance there may have any prearranged signification. As shown, itindicates that the line with which it is associ;- ated is engaged; andconsequently its absence or disappearance from the opening 0 indicatesthat the said line is free. The signal being thus set by the act ofmaking the plug connection, conversation can be carried on over theconductor L from one telephone t to the other t the rapidly varyingvoice cur rents passing without material obstruction by the aid of thereactanceless shunt winding cl, which together with the magnetizingwinding 0 is indicated diagrammatically in Fig. 4. The withdrawal of theplug 19 or the reopening in any preferred way of the generator andsignal circuit brings about the demagnetization of the core a, and theconsequent retraction of the armature and depression of the engagingprojection j by means of the weight 2'; and the said projection strikingthe short lever Z causes the signal shutter k to resume its formerapproximately horizontal position and to disappear, thereby indicatingthat the line L is now disengaged.

I claim- 1. In a signal indicating appliance, a signal plate or shuttertending in virtue of its own weight to hang vertically and displayitself; a superior weight normally acting in opposition to the saidtendency, and thereby holding the said signal plate in a retracted andinvisible position; and electromagnetic mechanism controlling the saidsuperior-weight and adapted when operated, to free the said signal platetherefrom, the latter being automatically restored to its retracted andinvisible position when the electromagnetic mechanismis thrown out ofoperation substantially as specified.

2. An electromagnetic annunciator having an armature carrying a weightedarm, normally resting upon a lever extension of a signal shutter orplate for automatically restoring the plate to and holding it in aretracted position, said plate being adapted to fall by its own weightwhen released from the superior weight of the arm through the attractionof the armature by its magnet, substantially as described.

3. An annunciator having a shutter or signal plate which isautomatically restored to and normally held in a retracted or invisibleposition by a weighted armature lever when the armature controlling thesaid lever is unattracted by its magnet, and adapted when freed from thesaid weight by the operation of the said magnet, to fall by its ownweight into a position of display.

4. The combination with a telephone circuit of a self-settingannunciator comprising an electro-magnet connected directly-in saidcircuit and having a magnetizing helix and also a winding shunting theentire magnetiz-' ing helix and constituting a path of low impedance tovoice currents; a shutter or signal plate provided with a leverextension and adapted when freed from control to fall by its own weight,and a lever of superior weight to that of the signal plate attached tothe armature and normally resting upon said lever extension and adaptedwhen the armature is released from the attraction of said magnet towithdraw the signal-plate and retain it in its retracted position,substantially as described.

5; A signal device comprising an electromagnetic spool; an armature anda weighted armature lever therefor; and a signal shutter forming one armof a pivoted lever, and provided with a projecting heel piececonstituting the complementary arm thereof, the said heel piece beingnormally engaged and depressed by the weighted armature lever and thesaid shutter being thereby correspondingly elevated; and the saidshutter being adapted to assume a vertical position in Virtue of its ownweight, when thesaid weighted armature lever is disengaged from its heelpiece, on the excitation of the said electromagnetic spool;substantially as described.

In testimony whereof I have signed my name to this specification, in thepresence of two subscribing witnesses, this 1st day of September, 189;.

THEODORE SPENCER.

Witnesses:

GEO. WILLIS PIERCE, JOSEPH A. GATELY.

